CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of U.S. patent Ser. No. 12/531,235, entitled, “LOCKING ELECTRICAL RECEPTACLE,” filed on Sep. 14, 2009, which is the U.S. National Stage of PCT Application US2008/57149, entitled, “LOCKING ELECTRICAL RECEPTACLE,” filed Mar. 14, 2008, which claims priority from U.S. Provisional Application No. 60/894,849, entitled, “LOCKING ELECTRICAL RECEPTACLE,” filed on Mar. 14, 2007. This application also claims priority form U.S. Provisional Application Ser. No. 61/221,793, filed on Jul. 10, 2009. The contents of all of the above-noted applications are incorporated herein as if set forth in full.
A wide variety of electrical connectors are known to provide electrical contact between power supplies and electrical devices. Connectors typically include prong type terminals, generally referred to as plugs, and female connectors designed for receiving the prong type terminals, generally referred to as receptacles, often described as electrical outlets, or simply outlets. The most common types of outlets include a pair of terminal contacts that receive the prongs of a plug that are coupled to “hot” and “neutral” conductors. Further, outlets may include a terminal contact that receives a ground prong of a plug. A variety of standards have been developed for outlets in various regions of the world.
Regardless of the standard at issue, the design of the aforementioned most common plug and receptacle system generally incorporates a friction only means of securing the two in the mated position. The frictional coefficient varies depending on a variety of conditions, including, but not limited to, manufacturing processes, foreign materials acting as lubricants, and wear and distortion of the assemblies. This characteristic results in a non-secure means of interconnecting AC power between two devices. It is arguably the weakest link in the power delivery system to electrical or electronic devices utilizing the system. However, it has been adopted worldwide as a standard, and is used primarily due to low cost of manufacture, ease of quality control during manufacture, and efficient use of space for the power delivery it is intended to perform.
The primary limitation of this connection technique is simply the friction fit component. In some applications where the continuity of power may be critical, such as data or medical applications, a technique to secure the mated connection may be desirable to improve the reliability. This may especially be true in mechanically active locations, such as where vibration is present, or where external activity may cause the cords attached to the plugs and receptacles to be mechanically deflected or strained in any manner.
It is against this background that the locking electrical receptacle of the present invention has been developed.
The present invention is directed to securing an electrical connection. In some cases, mating plug and socket electrical connections may be the least secure link in the power delivery system. Conventionally, these connections are secured only by means of a friction fit. A number of factors may affect the security of this connection. The present invention provides a variety of locking mechanisms whereby the very forces that would otherwise tend to pull the connection apart serve to actuate the clamping mechanism thereby securing the mated pair. The invention is of simple construction and highly reliable in operation. Moreover, the invention can be implemented simply in connection with new or retrofitted receptacle devices. Thus, the system is compatible with existing plugs and other infrastructure.
In accordance with one aspect of the present invention, an apparatus is provided for use in securing an electrical connection. The electrical connection is formed by a mating structure including prongs of a male assembly and receptacles of a female assembly (e.g., a cord cap or outlet receptacle) where the connection is broken by withdrawal of the prongs from the receptacles. It is noted that a wall outlet receptacle is generally female, while cord caps may be either male or female. The apparatus includes a clamping element movable between a clamping configuration, where the clamping element holds the mating structure in a connected state, and a release configuration. An activating element urges the clamping element into the clamping configuration responsive to a force tending to withdraw the prongs from the receptacles. In this manner, a force that would otherwise tend to pull the connection apart will now cause the apparatus of the present invention to clamp the connection in a secure state.
A variety of structures are possible to implement the noted clamping functionality. Such structure may be associated with the male assembly and/or the female assembly. In one implementation, the apparatus is implemented solely in the female assembly. For example, the clamping element may act on one or more of the prongs of the male assembly. In a particular implementation the clamping element acts on a ground prong, maintained at ground potential, such that it is unnecessary to consider potentials applied to the clamped prong in relation to the design of the clamping element. This also enables or facilitates compatibility with life safety/code regulations. However, it will be appreciated that other prongs may be additionally or alternatively engaged.
As noted above, the clamping element may include a contact surface for contacting one or more of the prongs in the clamping configuration. In this regard, the activating element may translate movement of the prongs in relation to the receptacle into movement of the contact surface into the clamping configuration. For example, movement of the prongs may be translated into rotational movement of the contact surface into an abutting relationship with the clamped prong. The apparatus may further include a release element for moving the clamping element into the release configuration. For example, the release element may be operated by a user by squeezing, sliding, pulling or pushing an element of the plug housing. In one implementation, a cord cap housing may be formed in two sections that are interconnected for sliding relative to each other in telescoping fashion. The clamping element can then be engaged manually by the user or automatically in response to a tension on the cord or section of the cord cap hence engaging the lock, and later released by selecting and sliding the corresponding section of the sliding housing section to the release position. It will be appreciated that the housing section can thus be readily accessed to release the clamping element even in crowded environments (e.g., in a data center rack). Moreover, the housing section to be gripped for releasing the clamping element may be color coded or otherwise conspicuously identified to assist users. Also, a variety of methods can be used to indicate if the clamping mechanism has been released at one time.
In accordance with another aspect of the present invention, a method for using a securing device is provided. The securing device includes a clamping element and an activating element as described above. The user can activate the securing device by inserting the prongs of the male assembly into the receptacles of the female assembly or by separately manipulating a locking actuator. In this mated arrangement, the electrical connection is secured as described above. The user can further deactivate the securing device by forcing the clamping element into the release configuration, for example, by squeezing the housing of the male assembly or sliding the housing section or actuating a tab or button or knob that is part of the cord cap or other means. In this manner, the electrical connection can be simply secured and released as desired by the user.
In accordance with a further aspect of the present invention, the release tension of a locking electrical receptacle can be selected in relation to a defined standard so as to avoid damage to a cord cap, cordage or plug or to meet a standard in relation thereto. In this regard, the release tension of the locking receptacle can be adjusted by varying, among other things, the geometry, thickness, material qualities and detail shaping of a clamping mechanism. It has been recognized that setting the release tension too high could result in damage to the receptacle housing, cordage or a mating plug which could, in turn, result in exposed wires and a safety hazard. Moreover, standards may be defined for release tension in relation to such concerns or others. An associated methodology in accordance with the present invention involves providing a locking electrical receptacle with a clamping element; determining a release tension limit for the receptacle in relation to a standard for safe operation of the electrical connection; determining a specification or setting of the clamping element to conform to the release tension limit; and constructing, or setting an adjustment mechanism of, the locking electrical receptacle in accordance with the specification or setting. For example, the release tension can be coordinated with a structural specification of an end cap or plug or cord so as to substantially ensure that the end cap or plug or cord will not break or fail due to strain associated with excessive release tension. In this manner, the characteristics of the locking electrical receptacle can be varied to address safety concerns or related standards or to match a desired setting of a user (which may change from time-to-time or depending on the application at issue).
In accordance with a still further aspect of the present invention, a strain relief mechanism is provided in connection with a locking mechanism of an electrical connection. As noted above, a potential concern in relation to a locking electrical connection is damage to an end cap, plug, cord or other structure, particularly where a high relief tension is desired. To alleviate such concerns, a strain relief structure is provided for transmitting a strain, associated with operation of a clamping mechanism for holding mating connection structure in a connected state, from the clamping mechanism to a power cord or other structure. For example, a clamping mechanism may be provided in a receptacle end cap for engaging one or more prongs of a plug. In such a case, strain relief structure may be provided that extends across the length of the end cap from the clamping mechanism for attachment to the power cord, e.g., by crimping, welding or otherwise joining. Alternatively, the strain may be transmitted to other structure separate from a receptacle/plug, such as a wall receptacle support structure. The strain relief mechanism thereby avoids hazards associated with undue stress on the end cap or other structure and reduces or substantially eliminates the need for other structural enhancement of the end cap or other structure.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A-1C illustrate the operation of an embodiment of a clamping mechanism in accordance with the present invention.
FIGS. 2A-2B illustrate an embodiment of a locking electrical receptacle in accordance with the present invention.
FIGS. 3A-3B illustrate an application for the locking electrical receptacle shown in FIGS. 2A-2B.
FIGS. 4A-4C illustrate an apparatus for providing a locking feature for a standard receptacle in accordance with the present invention.
FIG. 5 illustrates an embodiment of a standard duplex locking receptacle in accordance with the present invention.
FIGS. 6A-6B illustrate an embodiment of a locking receptacle that includes a cam lock in accordance with the present invention.
FIGS. 7A-7D illustrate an embodiment of a device for locking a mating assembly of a plug and receptacle in accordance with the present invention.
FIGS. 8A-8C illustrate an embodiment of plug that includes a toggle locking mechanism in accordance with the present invention.
FIGS. 9A-9B illustrate another embodiment of a plug that includes a divergent spring tip locking mechanism in accordance with the present invention.
FIGS. 10A-10B illustrate a further embodiment of an end cap incorporating a locking mechanism in accordance with the present invention.
FIGS. 11A-11B illustrates an alternative shaping of a spring prong retainer in accordance with the present invention that enables improved cord retention and increased overall strength.
FIG. 12 is a perspective view of an alternative embodiment of a spring prong retainer in accordance with the present invention.
FIGS. 13A-15B show an alternative embodiment of a locking spring prong retainer electrical receptacles and spring prong retainers in accordance with the present invention.
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that it is not intended to limit the invention to the particular form disclosed, but rather, the invention is to cover all modifications, equivalents, and alternatives falling within the scope and spirit of the invention as defined by the claims.
FIGS. 1A-1C illustrate the operation of an embodiment of a clamping mechanism for securing a mated electrical connection that may be included in a locking receptacle of the present invention. In each of the FIGS. 1A-1C, the bottom portion represents a side view of a prong 16 and a clamping mechanism 12, while the top portion represents a perspective view. Referring first to FIG. 1A, the prong 16 of a plug is shown prior to insertion into a receptacle 10. The prong 16 may be a ground prong of a standard plug (e.g., an IEC 320 plug, a NEMA 5-15, or the like) and may be various sizes and shapes. Further, the receptacle 10 may be the ground receptacle or other receptacle(s), of a standard outlet (e.g., a NEMA standard cord cap, an IEC 320 cord cap, or the like) that is operative to receive a standard plug. The receptacle 10 also includes the clamping mechanism 12 that is coupled to a pivot 14. The clamping mechanism 12 includes an aperture that is sized to be slightly larger than the prong 16, such that the prong 16 may only pass through the aperture when the length of the clamping mechanism is substantially perpendicular to the length of the prong 16. That is, the design of the clamping mechanism 12 is such that a simple slide on and capture technique is utilized.
FIG. 1B illustrates the prong 16 when inserted into the receptacle 10. As shown, the prong 16 passes through the aperture in the clamping mechanism 12 and into the receptacle 10, such that the corresponding plug and outlet are in a mated position. The clamping mechanism 12 further may include a stop (not shown) to prevent the clamping mechanism 12 from pivoting during the insertion of the prong 16. In this regard, during insertion of the prong 16, the length of the clamping mechanism 12 will remain substantially perpendicular to the length of the prong 16, which permits the passage of the prong through the aperture of the clamping mechanism 12.
FIG. 1C illustrates the gripping function of the clamping mechanism 12 in reaction to a force on the prong 16 that tends to withdrawal the prong 16 from the receptacle 10. In reaction to a withdrawal of the prong 16, the clamping mechanism 12 angularly deflects (i.e., rotates) about the spring pivot 14, causing the aperture in the clamping mechanism 12 to grip the prongs 16. Thus, the very force that tends to withdraw the prong 16 from the receptacle acts to actuate the clamping mechanism 12 to engage the prong 16, thereby preventing the withdrawal of the prong 16, and maintaining the electrical connection of the mated assembly. The clamping mechanism 12 may be constructed of any suitable material, including a high strength dielectric with an imbedded metallic gripping tooth. An all-metallic clamping mechanism may also be used if the prong 16 is a ground prong. In this regard, an all-metallic clamping mechanism may be used, e.g., for other prongs, though modifications may be required to obtain approval by underwriting bodies.
FIGS. 2A-2B illustrate a cross section of one embodiment of a locking electrical receptacle 20. The receptacle 20 is an IEC type 320 cord cap receptacle that includes a locking mechanism. The receptacle 20 includes an inner contact carrier module 24 that houses contact sockets 26 and 28. Attached to the contact sockets are wires 36 and 38 that extend out of the receptacle 20 though a cord 34. The carrier module 24 may be attached to a cord strain relief 32 that functions to prevent the cord from separating from the cord cap or otherwise resulting in damage to the assembly when a force is applied to the cord 34. A spring prong retainer 40 is disposed adjacent to a surface of the carrier module 24, and extends across a prong-receiving portion 44 of the receptacle 20. One end of the spring prong retainer 40 is bent around the end of the inner contact carrier module 24, which secures it in the assembly (underneath the over-molded material 32).
Alternatively, the spring prong retainer 40 may be secured to the inner contact carrier module 24 by a screw or other fastener, and/or embedded in the module 24. A section of the spring prong retainer 40 that is embedded in the module 24 or alternatively secured in the cord cap via over molded material may be configured (e.g., by punching a hole in the embedded section and/or serrating the edges or otherwise shaping it) to enhance the anchoring strength in the embedded section. The other end of the spring prong retainer 40 is in contact with a telescopic lock release grip 22. Similar to the clamping mechanism 12 shown in FIGS. 1A-1C, the spring prong retainer 40 includes an aperture sized to permit the passage of the ground prong of a plug into the socket 26. The aperture in the spring prong retainer 40 may be sized to be slightly larger than one prong (e.g., the ground prong) in a standard plug such that the aperture may function as the clamping mechanism for the locking receptacle 20. It can be appreciated that prongs with different cross-section shapes, for example round prongs, can use the retention mechanism described herein, with a suitable modification of the aperture shape and geometry of the spring prong retainer. Such modifications may be specific to the various shapes of the cross section of various prong types. Such variations will function in substantially the same manner as the retention mechanism described herein. The spring prong retainer 40 may further be shaped and constructed, as will be discussed in more detail below, to inhibit contact with other prongs and provide a desired release tension. Moreover, the retainer 40 may be retained within a recessed channel formed in the module 24 to further inhibit transiting or side-to-side displacement of the retainer 40. The operation of the clamping feature of the spring prong retainer 40 is discussed in detail below.
FIG. 2A illustrates the locking receptacle 20 when there is little or no strain on the cord 34. As shown, the portion of the spring prong retainer 40 disposed in the prong-receiving portion 44 of the receptacle 20 is not in a substantially vertical position. Similar to the operation of the clamping mechanism 12 shown in FIGS. 1A-1C, the apertures of the spring prong retainer 40 in this configuration will allow the prongs of a plug to pass freely into the socket 26 when the prong is inserted. This is due to the unrestricted change of position of the spring prong retainer 40 to the substantially vertical position as the prongs of a plug acts upon it.
FIG. 2B illustrates the locking receptacle 20 when a force is applied to the cord 34 of the receptacle 20 in the opposite direction of the grip release handle 30. This is the “release position” of the receptacle 20 and is shown without the mating prongs for clarity of operation. Actions that initiate this position are illustrated in FIGS. 3A and 3B.
FIG. 3A illustrates the operation of the locking electrical receptacle 20 shown in FIGS. 2A-2B. When a prong 54 of a plug 50 first enters the receptacle 20 via an aperture in the lock release grip 22, it encounters the spring prong retainer 40, which is not in the perpendicular orientation at that time. Upon additional insertion, the spring prong retainer 40 is deflected into the perpendicular position by the force applied to it by the prong 54. The prong 54 then passes through the aperture in the spring prong retainer 40 and into the contact socket 26, making the electrical connection as required. Upon release of the insertion force, and when no axial strain is applied to the mated plug 50 and receptacle 20, the spring prong retainer 40 is only partially displaced from the perpendicular axis. It is noted that there is little separation between the forward-most surface of the plug 50 and the end of the receptacle of carrier module 24 adjacent the plug 50 in this connected configuration, i.e., the prong extends to substantially the conventional extent into the receptacle.
FIG. 3B illustrates in an exaggerated manner the condition of applying axial tension to the cord 34 of the receptacle 20. A slight retraction motion pulls on the spring prong retainer 40, thereby increasing the angle of grip and subsequent tightening of the offset angle of the spring prong retainer 40 and prong 54. The receptacle 20 and the plug 50 are then fully locked in this condition. Upon application of axial tension between the release grip handle 30 and the plug 50, the position of the spring prong retainer 40 is returned to the near-perpendicular position as illustrated in FIG. 3A, thereby releasing the spring prong retainer 40 from the prong 54. Upon release, the receptacle 20 is easily separated from the plug 50. Because the release grip handle 30 is mounted to slide in telescoping fashion with respect to the carrier module 24 and can be gripped for prong release from the top or sides, the locking mechanism can be easily released even in crowded or space limited environments such as in data centers.
FIGS. 13A-13C illustrate an alternative spring prong retainer. In the embodiment described above and illustrated by FIGS. 1A through 3B, the retention gripping points are along the flat, or semi-flat surfaces of the narrow axis of the prong. The apertures are rectangular in shape and the top and bottom of the rectangle comprise the contact locations on the prong. Forces applied to those contact points are limited to the relationship of the precision of the prong dimensions to the hole dimensions. In the embodiment of FIG. 13A, the aperture has a rectangular top and a bottom half that narrows down or tapers. This design of aperture contacts the prong at three locations 1100, 1101, 1104 (see FIG. 13A—Exaggerated View), on the top of the prong and on each of the sides at the bottom.
A significant increase in the gripping force is possible due to the amplification of the pull torque via not only the angular displacement of the spring prong, but also the wedging effect at the two adjacent contact points 1100, 1101 at each corner of the narrow axis of the mating prong 1103. As pull force is exerted on the hook tab 1106 of the spring retainer 1110, an initial action occurs as described for the spring prong retainer in FIGS. 1A thru 1C. After the initial contact is made at points 1100, 1101, 1104 during the attempt to withdraw the mating prong 1103, the forces applied to the mating prong 1103 are amplified by the inclined planes of the bottom of the slot 1100 1001. The tension force formed in the early stage of gripping by the axial displacement of the spring prong retainer 1110 about the fulcrum point 1105 is amplified greatly to apply a compressive force at the contact points of the mating prong 1103 and the spring prong retainer bottom contact points 1100 and 1101. This force is multiplied by about 10 to 1 due to the tension amplification of the spring prong retainer 1110 about the fulcrum 1105. A total force amplification of about 80 times can be achieved by this method. It should be appreciated that by adjusting the angles of the inclined planes 1100 and 1101, and the geometry of metal 1104 forming the fulcrum 1105, that various amplifications of force can be achieved. It should also be appreciated that by varying the amplification force, the spring prong retainer can be tuned to optimally engage with a variety of mating prong materials and finishes.
Due to this amplification, and the relatively small contact area between the spring prong retainer, inclined planes 1112 (FIG. 13C) 1110, 1101 and the mating prong 1103, forces at least as high as 30,000 pounds psi (30 Kpsi) are possible, thus ensuring positive gripping of the mating prong 1103. It should be appreciated that use of this alternate method of mating prong capture is also more tolerant of manufacturing variances in the prongs.
FIG. 13B illustrates the release methodology for this alternate spring prong retainer. It is similar to that of the spring prong retainer previously described. As release force is applied to the end of the spring prong retainer 1111 by the face of the outer shell 1116, the surface of the spring prong retainer 1110 becomes more perpendicular to the mating prong 1103. In turn, the point of contact at the fulcrum 1105 is disengaged and the mating prong would normally be free to be extracted, as described for spring prong retainer 40 of previous embodiments. However, at this point the lower contact points (illustrated in FIG. 13A) 1100, 1101 have the mating prong 1103 captured between them, and likely a small deflection of the metal of the mating prong 1103 has occurred at those points. The mating prong 1103 is therefore probably not yet released. As the outer shell 1116 compresses the face of the spring prong retainer 1110, the molded-in ramp in the outer shell 115 begins to push the spring prong retainer down and in turn pushes the lower contact points 1100 and 1101 (illustrated in FIG. 13A) down off of the mating prong 1103. Eventually the entire assembly is disengaged from the mating prong 1103.
It should be appreciated that the shape of the spring prong retainer (illustrated in FIG. 13A) contributes to the disengagement characteristics as well. The shoulders of the spring prong retainer 1107 are placed such that, upon force being applied to the spring prong retainer to release, the shoulders contact the interior surface of the outer shell 1116. Continued rotation of the face of the spring prong retainer closer to perpendicular to the mating prong 1103 results in the entire face of the spring prong retainer 1111 to be forced down. This action, in conjunction with the action of the ramp cast into the outer shell 1115 results in positive down force on the spring prong retainer disengaging the lower contact points 1100 and 1101 (illustrated in FIG. 13 A) from the mating prong 1103.
FIGS. 14A-15B illustrate an alternate capture mechanism. FIG. 14C illustrates the principal mechanical components of the capture mechanism. A saddle and strain relief component 1401 is placed into the plastic connector carrier of the injection molded receptacle. A capture toggle 1402 is inserted into the two holes at the end of the saddle 1401. The opposite end of the saddle and strain relief component 1401 is the crimp ring that clamps around the cord end just beyond the start of the outer jacket or other suitable location depending on the design of the cord. It will be appreciated that if, e.g., for ease of manufacturing, it is designed to make the strain relief and clamping mechanism from different materials, such as metals of different properties, than the carrier or other cord attachment mechanism, this can easily be done, by separating the attachment method to the cord, such as a crimp ring from the strain relief piece and then connecting them mechanically. It should be appreciated that the strain relief mechanism described herein can be used with the two additional retention mechanisms described earlier
FIG. 14A illustrates the assembly of the saddle 1401 and the cord assembly 1400, 1407. The cord assembly includes the main cord 1400, an electrical interface terminal 1406, and the interior conductor 1407 of the aforementioned cord that connects to the terminal 1406. The terminal 1406 rests in the closed end of the saddle and the strain relief component 1401 and the two components are aligned along the long axis by relief ways in the outer contact carrier (not shown). If desired or needed, the terminal 1406 can be mechanically attached or bonded to the saddle and strain relief component 1401 for ease of assembly, greater strength, or other purposes. The capture toggle 1402 is placed during manufacture in the saddle between the two holes in the saddle 1401. The pre-load spring 1403 will press upon the capture toggle 1402 while the release actuation rod 1404 rests against the opposite side of the toggle.
FIG. 14B shows a side view of this assembly. The outer contact component carrier 1409 houses and contains each of the components and prevents injection molding plastic from entering the interior of the carrier during the final outer over-mold injection process. FIG. 14B also helps understand the basic operation of the capture assembly. When the prong of the inserted plug 1405 is inserted into the receptacle, it enters into the plastic carrier 1409, then into the terminal 1406, and eventually passes under the toggle 1402 until it is fully inserted and is in the position shown. If tension is applied to the power cord in attempt to extract it from the mated plug, the force is transmitted from the cord to the prong 1405 and hence to the toggle 1402 (via the strain relief component and saddle 1401) which is pressed against the top of the prong 1405 by the pressure of the saddle 1401 on the bottom of the prong 1405, transmitted through the electrical terminal 1406. The toggle is pre-loaded against the top of the inserted prong of the plug connector 1405 by the spring 1403. As can be appreciated the shape of the toggle where it presses down on the prong can be shaped to control the application of the clamping force to the prong, for example, the toggle can have a groove to control the force on the prong so as not to twist it. This can also be done for the base of the saddle and mating terminal if desired or necessary. A suitably shaped insert between the saddle/strain relief 1401 and a terminal shaped to match the insert could accomplish this function. As the force applied to the cord 1407 causes minute movement along the major axis of the assembly, the mating prong also begins to attempt to retract and the toggle begins to rotate in such a manner as to force down the top of the inserted mating prong of the plug connector 1405, squeezing it tighter into the terminal 1406, and hence the terminal is squeezed into the saddle 1401. The friction between the terminal 1406, the mating prong of the plug connector 1405 and the saddle 1401 increases rapidly to a point where the movement is ceased. The pressing down of the mating prong 1405 onto the electrical terminal 1406 also improves the quality of the electrical connection. The prong of the plug connector 1405 is now functionally locked to the saddle and strain relief component 1401, and hence the cord 1407. FIG. 15A illustrates from an end-on view the relationship of all of the components involved in the locking of the components together. The prong of the inserted plug 1405 is located in the terminal 1406, which is sandwiched between the prong 1405 and the saddle 1401.
FIG. 14B illustrates the mechanism to release the connection of the toggle 1402 and the prong of the plug connector 1405. The opposite end of the release rod 1404 can extend through the entirety of the receptacle and protrude out the back of the connector or assembly where it is user accessible. The release rod 1404 can also be actuated by other means such as is shown in FIG. 14D. A telescopic section of the cord cap 1412 which includes a mechanical linkage 1408 can push the release rod 1404 against the toggle 1402 when the telescoping section 1412 is pulled back by the user to separate the plug assembly from the receptacle assembly (line 1413 indicates the fully inserted depth of the front face of the plug). In this regard, the range of motion of the telescoping section 1412 is controlled by elements 1410 and 1411. Pressure on the opposite end of the rod 1404 transmits to the back of the toggle 1402 and compresses the spring 1403 slightly. This action rotates the bottom of the toggle 1402 up and away from the prong of the inserted plug connector 1405 and reduces or eliminates the contacting force between the toggle 1402 and the mating prong 1405 allowing the mating prong to move in the retraction direction. The receptacle can then be separated from the plug. The system can be designed so that the spring 1403 functions to return the telescopic section 1412 to the locked configuration when the user releases the section 1412.
FIG. 15A illustrates the end-on view of the principal components of the inserted prong of the plug connector 1405 and the locking components of the receptacle in cross section. As mentioned previously, the toggle 1402 has been rotated into a position such that it is pressing on the prong of the inserted plug connector 1405. The prong 1405 is in turn pressing on the terminal 1406 and in turn the terminal 1406 is pressing on the bottom of the saddle 1401. It should be appreciated that as axial tension on the cord is increased the downward force exerted by the toggle 1402 will also increase. With suitable angles selected, and suitable dimensions of the components, the force amplification can be about 10 to 1. In other words, 10 pounds of strain force on the cord will result in about 100 lbs of force exerted on the prong.
It also should be appreciated that the bottom of the saddle and strain relief component 1401 can be manufactured with a crown shape as shown. This crown shape allows the bottom of the saddle and strain relief component 1401 to act like a leaf spring when pressed down by the prong. The spring in the bottom of the saddle allows a very controllable and predictable force to be applied to the prong 1405 by the combination of the toggle pressing down on the prong and the spring resisting that force as transmitted by the prong and terminal. The maximum clamping force of the toggle on the prong is controlled by the resistance and travel of the spring. This feature can be used as follows. When strain is put on the cord to pull apart the connection, the toggle increases its force on the prong and eventually a point will be reached where the spring in (or under as described in alternative embodiments discussed below) the bottom of the saddle and strain relief component 1401 starts to flatten out. This action allows the distance from the base of the saddle and strain relief component 1401 and the tip of the toggle 1402 to increase, allowing the toggle 1402 to rotate. As the tension on the cord continues to increase, a point will be reached where the distance between saddle and strain relief component 1401 and the toggle 1402 is great enough that the toggle 1402 will rotate and be perpendicular to the prong. At this point the tab on the toggle 1402 can no longer add any additional pressure to the prong 1405, and the prong 1405 will move under the tension applied to the cord 1407 which separates the plug and receptacle. It should also be appreciated that the tension at which the release occurs can be reliably predicted to occur and can be varied by the strength and travel of the spring. The design is somewhat tolerant of manufacturing variances of both the inserted connector prong and the mechanical components of the locking mechanism. It should also be appreciated that the tension at which the mated connection releases under strain can be reliably pre-set.
In this design, FIG. 15A illustrates the end-on view of the saddle and strain relief component 1401 with the cord crimp end away from the viewer. The crown spring depicted in the front 1521 view has the function of controlling the release point of the connected assembly under strain conditions. In FIG. 15B the crown spring is shown with a hole 1541 that is used to modify the strength and travel of the crown spring. However, other means such as the thickness or type or temper, etc., of the material used can be selected to control the spring function. Observing that the location of the hole 1541 is located directly under the saddle section of the saddle and strain relief component 1401, it should be appreciated that the strength of the crown spring action is modified. The absence of a hole will allow maximum resistance to compression of the spring crown, and a large hole will introduce significant reduction in spring strength. By reducing the spring strength, the release point of the mated connector components is subsequently reduced. Hence, the retention capacity of the locking receptacle can reliably set to specific release tensions. It will be appreciated that this design further promotes ease and lower cost of manufacture. The die that stamps the strain relief can have an insert that can be changed to vary the size of the hole 1541 in the leaf spring for various values of release tension. Other means of setting the strength and travel of the spring can be used, for example the thickness and shape of the material or other means. Also, other means that use a uniform or variable strength spring of a suitable type (hairpin, leaf, elastomer, etc) to press on the bottom of the saddle 1401 directly below the toggle 1402 can be used. The saddle in this case would not need to incorporate a spring, the spring would be separate from the saddle. This would permit the addition of a factory and/or end user spring force adjustment mechanism, such as a screw. This mechanism would control the strength and travel of the spring pressing on the saddle and hence the release tension of the gripping mechanism as was described earlier. The range of adjustment could be controlled to meet any needed requirement. It can be appreciated that being able to reliably set the release tension is extremely useful—it allows a locking cord to be made that does not require a separate release mechanism. The release is done by the locking mechanism at the desired tension level.
FIG. 14C depicts an orthogonal view of the saddle and strain relief component 1401. The grip ring 1408 at the end of the saddle and strain relief component 1401 is shown as an integral part of the saddle and strain relief component 1401. This ring can also be a separate compression ring that is inserted over the end of the saddle and strain relief component 1401, where the end of the saddle and strain relief component 1402 can be shaped appropriately to be sandwiched between said compression ring and the end of the attached cord. The alternate method of attaching the saddle and strain relief component 1401 to the cord is mentioned due to the potential difficulties in compound heat treatment along the length of the saddle and strain relief component 1401. The saddle end of the saddle and strain relief component 1401 will generally be heat treated, while the crimp ring end must remain malleable. Although it is possible to manufacture the saddle and strain relief component 1401 with these characteristics, it may be more economical to manufacture an alternately shaped saddle and strain relief component 1401 and assemble it to the cord with a separate compression ring. It can be appreciated that the retention mechanism described will work well with other shapes of prongs than those illustrated, which are flat blade type prongs. For example, the retention mechanism will work well with round prongs such as used in NEMA 5-15 and other plugs. Only minor changes are needed such as shaping the end of the toggle where it contacts the round prong to have a suitable matching shape and thickness to optimize how the force is applied to the material of the prong. This is desirable, since many round prongs are formed of tubular, not solid material and therefore can be deformed or crushed by too much force applied to too small an area of the material they are made of. Similarly, the bottom of the saddle and/or the electrical contact could be shaped to spread the clamping force more evenly on to the round prong and/or an insert between the saddle and the terminal could be used for this purpose. Although the embodiment of FIGS. 14A-15B has been illustrated and described in relation to a conventional cord cap, it will be appreciated that similar structure can be incorporated into other types of receptacle devices including, for example, the structure described in PCT Application PCT/US2008/57140 entitled, “Automatic Transfer Switch Module,” which is incorporated herein by reference.
By utilizing a clamping mechanism (e.g., the spring prong retainer 40) that captures the ground prong of the plug 50 only, the safety of the receptacle 20 may be greatly improved. In this regard, the effect of the application of various electrical potentials to clamping mechanism of the assembly is avoided, which may simplify the manufacturing of the receptacle, as well as improve its overall safety.
FIGS. 4A-4C illustrate a locking device 60 for providing a locking feature for a standard cord-cap receptacle. As shown in FIG. 4A, the locking device 60 includes a top holding member 62 and a bottom holding member 64 for positioning the locking device 60 onto a standard receptacle. The locking device 60 also includes a portion 66 that couples the holding member 62, 64 in relation to each other to provide a secure attachment to a receptacle. The locking device 60 also includes a clamping mechanism 68 that is coupled to a pivot 70. The operation of the clamping mechanism 68 is similar to that of the clamping mechanism 12 illustrated in FIGS. 1A-1C. It can be appreciated that the other clamping mechanisms described earlier could also be employed. As described earlier some of these eliminate the need to provide a separate release and could optionally provide a factory and/or user adjustable release tension feature. The locking device 60 may also include a release mechanism 72 that is operative to enable a user to disengage the clamping mechanism 68 when it is desired to remove a receptacle from a plug.
FIG. 4B illustrates the locking device 60 positioned onto a standard receptacle 80. To facilitate the installation of the locking device 60, the holding members 62 and 64 may be made of an elastic material such that a user may bend them outward and position the device 60 onto the receptacle 80. For example, the holding members 62, 64 may be made of plastic. Further, as shown, the holding members 62, 64 are shaped such that once installed onto the receptacle 80, the device 60 is not easily removed without a user deforming the holding members 62, 64. That is, the holding members 62, 64 may be shaped to closely fit onto standard receptacle, such that normal movements will not disengage the device 60 from the plug 80.
FIG. 4C illustrates the operation of the locking device 60 when the receptacle 80 is mated with a standard plug 84. The ground prong 86 of the plug 84 passes through an aperture in the clamping mechanism 68 and into the receptacle 80. If a withdrawing force tending to break the mated connection is applied to either the cord of the standard plug 84 or the cord of the receptacle 80, the clamping mechanism 68 will rotate, causing it to grip the ground to prong of the standard plug 84, thereby maintaining the electrical connection. If the user desires to break the connection, the user may engage to release element 72, which is operative to maintain the clamping mechanism 68 in a substantially perpendicular position relative to the ground prong 86, thereby permitting the prong 86 of the standard plug 84 to be withdrawn from the receptacle 80. It should be appreciated that although one particular embodiment of a locking device 60 has been illustrated, there may be a variety of ways to implement a locking device that may be retrofitted to a standard receptacle that uses the techniques of the present invention.
FIG. 5 illustrates an embodiment of a standard duplex locking receptacle 100. In this embodiment, clamping mechanisms 112 and 114 are integrated into the receptacle 100. The top portion of the receptacle 100 includes sockets 102, 104 for receiving the prongs 128, 130, respectively, of a standard plug 126. Similarly the bottom portion of the receptacle 100 includes sockets 106, 108 for receiving a second standard plug. The clamping mechanisms 112, 114 are each pivotable about the pivots 116, 118 respectively. Further the receptacle 100 also includes release elements 120, 122 that are operative to permit a user to break the connection when desired. The operation of the clamping mechanism 112, 114 is similar to that in previously described embodiments. That is, in response to a force tending to withdraw the plug 126 from the receptacle 100, the clamping mechanism 112 rotates in the direction of the plug 126, and engages the ground prong 130, preventing the mated connection from being broken. If a user desires to intentionally removed the plug 126 from the receptacle 100, the user may activate the release mechanism 120 and withdraw the plug 126. It can be appreciated that the other clamping mechanisms described earlier could be employed in a standard duplex locking receptacle. As discussed earlier, some of these eliminate the need to provide a separate release mechanism and could optionally provide a factory and/or user adjustable release tension feature.
FIGS. 6A-6B illustrate side views of a receptacle 150 that includes a cam lock 152 for locking the prong 162 of a plug 160 to preserve a mated connection between the receptacle 150 and the plug 160. FIG. 6A illustrates the receptacle prior to the insertion of the plug 160, and the cam lock 152 may hang freely from a pivot 153. In this regard, an end of the cam lock 152 is positioned in the opening of the receptacle 150 that is adapted for receiving the prong 162 of the plug 160.
FIG. 6B illustrates the mated connection of the plug 160 and the receptacle 150. As shown, in the mated position the prong 162 has deflected the cam lock 152 about the pivot 153, causing the cam lock 152 to be angled away from the plug 160 and abutted with the prong 162. Thus, when an axial strain is applied to the plug 160 or the receptacle 150, the friction between the cam lock 152 and the prong 162 will tend to force the cam lock 152 downward toward the prong 162, which functions to retain the plug 160 in its mated position. If a user desires to intentionally remove the plug 160 from the receptacle 150, they may press the actuating mechanism 154, which may be operable to rotate the cam lock 152 out of the way of the prong 162, thereby enabling the user to freely withdraw the plug 160 from the receptacle 150. It should be appreciated that the cam lock 152 and the actuating mechanism may be constructed from any suitable materials. In one embodiment, the cam lock 152 is constructed out of metal, and the actuating mechanism 154 is constructed from an insulating material, such as plastic.
FIGS. 7A-7D illustrate a device 170 that may be used to secure a mated connection between a plug and a receptacle. As shown, the device 170 includes a top surface 173, a bottom surface 175, and a front surface 171. The three surfaces 171, 173, 175 are generally sized and oriented to fit around the exterior of a standard receptacle 178 at the end of a cord (i.e., a cord cap). The top and bottom surfaces 173 and 175 each include hooks 174 and 176, respectively, that are used for securing the device 170 to the receptacle 178 (shown in FIG. 7D). The operation of the hooks 174 and 176 is described herein in reference to FIG. 7D, which shows a side view of the device 170 when it is installed around the exterior of the receptacle 178. The hooks 174, 176 may be bent inward towards each other, and wrapped around an end 179 of the receptacle 178 to secure the device 170 to the receptacle 178. The other end of the receptacle 178 (i.e., the end with the openings 181 for receiving the prongs of a plug) may be abutted with the face surface 171 of the device 170.
The device further includes tabs 172 that are used to securing the prongs of a plug in place. The operation of the tabs 172 is best shown in FIG. 7B, which illustrates the device 170 when installed over the prongs 182, 184 of a plug 180. The plug 180 may be any plug that includes prongs, including typical plugs that are disposed in the back of electrical data processing equipment. As shown, when the device 170 is installed by sliding it axially toward the plug 180, the tabs 172 deflect slightly toward the ends of the prongs 182, 184. In this regard, if an axial force that tends to withdraw the device 170 from the plug 180 is applied, the tabs 172 will apply a downward force against the prongs 182, 184. Since the openings in the device 170 are only slightly larger than the prongs 182, 184, this downward force retains the prongs 182, 184 in their position relative to the device 170. Further, because the device 170 may be secured to a standard receptacle as illustrated in FIG. 7C, the tabs 172 prevent the connection between the receptacle 178 and the plug 180 from being broken. The device 170 may be constructed of any suitable non-conductive material. In one embodiment, the device 170 is constructed from a semi-rigid plastic. In this regard, the device 170 may be a single use device wherein a user must forcefully withdraw the installed device 170 from the prongs 182, 184 of the plug 180, thereby deforming the plastic and/or breaking the tabs 172. It should be appreciated that if a user desired to unplug the receptacle 178, they may simply unwrap the hooks 174, 176 from the end 179 and separate the mated connection, leaving the device 170 installed on a plug.
FIG. 8A illustrates a plug 190 that includes a locking mechanism prior to insertion into a receptacle 210. As shown in a simplified manner, the receptacle 210 includes recesses 212 and 214. Most standard receptacles include a recess or shoulder inside the openings that are adapted to receive the prongs of a plug. This recess may be present due to manufacturing requirements, such as the molding process used to manufacture the receptacles. Further, the need to include various components (e.g., electrical connections, screws, etc.) in the receptacles may cause the need for the small recesses. If the recesses are not already present, they could be designed into the receptacle.
The plug 190 uses the recess 214 to assist in creating a locking mechanism. As shown, a hollow prong 194 (e.g., the ground prong) of the plug 190 includes a toggle 196 that is attached via a pivot to the 193 inner portion of the prong 194. A spring 198, piston 199, and an actuating mechanism 200 function together to enable the toggle 196 to be oriented in a lock configuration (shown in FIG. 8B), and a release configuration (shown in FIG. 8C). In one embodiment, the spring 198 acts to bias the tab 198 in the release position, which may be a substantially aligned with horizontal position inside the prong 194. Furthermore, the actuating mechanism 200 may be operable to rotate the toggle 196 into the unlock position (shown in FIGS. 8C) where the toggle 196 retracts into the prong 194 at an angle substantially parallel to the body of the prong 190. A user may control the actuating mechanism 200 through a control switch 202, which may be positioned on the front of the plug 190.
FIG. 8B illustrates the plug 190 when in a mated position with the receptacle 210. As shown, the tab 196 has been placed in the lock position by the pressure asserted by the spring 198 and piston 199. In this configuration, the tab 196 will resist any axial force that tends to withdraw the plug 190 from the receptacle 210. This is the case because the recess 214 acts as a stop for the tab 196. Therefore, the plug 190 may be securely fastened onto the receptacle 210. FIG. 8C illustrates when a user desires to remove the plug 190 from the receptacle 210, they may depress the control switch 202 on the front of the plug 190, which causes the actuating mechanism 200 and the spring 198 to rotate the tab 196 into the release position.
FIGS. 9A-9B illustrate another embodiment of a plug 220 that includes a divergent spring tip locking mechanism prior to insertion into a receptacle 240. Similar to the plug 190 shown in FIGS. 8A-8B, the plug 220 may be adapted to work with the standard receptacle 240 that includes recesses 242 and 244. The plug 220 may include a hairpin spring 226 that is disposed inside a hollow prong 224 (e.g., the ground prong). In a release position, the ends 227 of the spring 226 are disposed inside of the prong 224 and adjacent to openings in the prong 224. The plug 220 may further include an actuating mechanism 228, couple to a control switch 230 on the front of the plug 220, for biasing the spring 226 into a lock position, where the ends 227 of the spring 226 protrude outside of openings in the prong 224 (see FIG. 9B).
FIG. 9B illustrates the plug 220 when installed into the standard plug 240. As shown, the actuating mechanism 228 has been moved axially toward the spring 226 into the standard receptacle 240, causing the ends 227 to spread apart and out of the openings in the prong 224. The openings of the prong 224 are aligned with the recesses 242 and 244 such that the ends of the spring 226 are disposed in the recesses 242 and 244 when in the lock position. Thus, as can be appreciated, when an axial force that tends to withdraw the plug 220 from the receptacle 240 is applied, the ends 227 of the spring 226 are pressed against the recesses 242 and 244, which prohibits the prong 224 from being removed from the receptacle 240. When a user desires to remove the plug 220 from the receptacle 240, they may operate the control switch 230 which causes the actuating mechanism to axially withdraw from the spring 226. In turn, this causes the ends 227 of the spring 226 to recede back into the prong 224, such that the user may then easily remove the plug 220 from the receptacle 240.
FIGS. 10A and 10B show a locking electrical receptacle 1000 according to a further embodiment of the present invention. The receptacle 1000 is generally similar in construction to the structure of FIGS. 2A-2B. In this regard, the illustrated receptacle 1000 includes an end cap formed from an outer lock release grip 1002 that is slideably mounted on an inner contact carrier module 1004. The inner contact carrier module carries a number of sockets or receptacles generally identified by reference numeral 1006. The illustrated receptacle 1000 further includes cord strain relief 1010 and spring prong retainer 1008.
FIG. 10B shows a perspective view of the spring prong retainer 1008. As shown, the retainer 1008 includes a number of gripping tabs 1012 for gripping the contact carrier module 1004. In this regard, the gripping tabs 1012 may be embedded within the molded contact carrier module 1004 so as to more firmly secure the retainer 1008 to the carrier module 1004. Alternatively, the tabs 1012 may be pressed into the carrier module 1004 or attached to the module 1004 by an adhesive or the like. In this manner, the tabs 1012 assist in securing the spring prong retainer 1008 to the contact carrier module 1004 and maintaining the relative positioning between the spring prong retainer 1008 and the contact carrier module 1004. It will be appreciated from this discussion below that this relative positioning is important in assuring proper functioning of the locking mechanism and controlling the release tension. The locking electrical receptacle of 1000 otherwise functions as described above in connection with FIGS. 2A-3B.
FIGS. 11A and 11B show a further embodiment of a locking electrical receptacle 1100. Again, the receptacle 1100 is generally similar to the structure described above in connection with FIGS. 2A and 2B and includes an outer lock release grip 1102, and inner contact carrier module 1104 including a number of receptacles 1106, and a cord strain relief structure 1110. The illustrated embodiment further includes a spring prong retainer 1108 incorporating strain relief structure. It will be appreciated that the locking mechanism of the present invention can result in significant strain forces being applied to the end cap in the case where large tension forces are applied to a plug against the locking mechanism. Such forces could result in damage to the end cap and potential hazards associated with exposed wires if such forces are not accounted for in the end cap design.
Accordingly, in the illustrated embodiment, the spring prong retainer 1108 includes strain relief structure for transmitting such strain forces directly to the power cord. Specifically, the illustrated spring prong retainer 1108 is lengthened and includes a cord grip structure 1114 at a rear end thereof. The cord attachment grip structure 1114 attaches to the power cord or is otherwise connected with a crimping band 1112 that can be secured to the power cord via crimping and/or welding, etc. or the like. In this manner, strain forces associated with operation of the spring prong retainer 1108 to grip prongs of a plug are transmitted directly to the power cord.
Various characteristics of the locking electrical receptacle of the present invention can be varied to control the release stress of the locking electrical receptacle. In this regard, the geometry, thickness, material qualities and detail shaping of the gripping component can be used to control the release tension of the locking mechanism. As an example, increasing the thickness and/or stiffness of the material of the gripping component increases the release tension of the locking mechanism.
The geometry of these spring prong retainers may also be varied to provide improved safety and performance. FIG. 12 shows on example in this regard. The illustrated spring prong retainer 1200, which may be incorporated into, for example, the embodiments of FIGS. 2A-2B, 10A-10B, or 11A-11B, includes a narrowed neck portion on 1202 between the flex point 1204 of the spring prong retainer and the prong engagement opening. This neck portion may provide a number of desirable functions. For example, the neck portion 1202 maybe positioned to provide greater clearance between the spring prong retainer 1200 and the other prongs of plug. In addition, the narrow portion 1202 may be designed to provide a defined breakpoint in the case of structural failure. That is, in the event breakage occurs due to stress or material fatigue, the neck portion 1202 provides a safe failure point that will not result in electrical hazards or failure of the electrical connection.
It can be appreciated that all of the retention mechanisms described herein that can have their release tension changed by varying their design parameters, can have a release tension that is coordinated with the receptacle design or a standard or specification so as to ensure that the cord cap or receptacle will not break resulting in a potentially hazardous exposure of wires. Thus, for example, it may be desired to provide a release stress of forty pounds based on an analysis of an end cap or receptacle structure, a regulatory requirement, or a design specification. The locking mechanism may be implemented by a way of a spring prong retainer as shown, for example, in FIGS. 2A-2B, 10A-10B and 11A-11B. Then, the material and thickness of the spring prong retainer as well as the specific geometry of the spring prong retainer may be selected so as to provide a release stress of 40 lbs. The locking mechanism with a release stress of 40 lbs can also be implemented in the toggle and saddle mechanism as shown, for example in FIGS. 14A-14D and 15A-15B. The values of these various design parameters may be determined theoretically or empirically to provide the desired release point.
The foregoing description of the present invention has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit the invention to the form disclosed herein. Consequently, variations and modifications commensurate with the above teachings, and skill and knowledge of the relevant art, are within the scope of the present invention. The embodiments described hereinabove are further intended to explain best modes known of practicing the invention and to enable others skilled in the art to utilize the invention in such, or other embodiments and with various modifications required by the particular application(s) or use(s) of the present invention. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art.